I made a sauce with frozen rhubarb and raspberry mixed with sugar and reduced it until there is hardly any juice left. I put the leftovers in a sealed container in the fridge. Would this still be good? Is there anyway to tell when this is going bad?

2 Answers 2


It depends on a lot of factors: what you're describing isn't much different from making jam, and homemade jam is good for about a month, once you open it. Assuming you got the temp high enough to kill all the bacteria, the time will depend entirely on PH and water content. The more acidic, and the less watery the better.

Generally things like this freeze well though, so, when in doubt, throw it in the freezer.


Without preservation the shelf life of your sauce is even less than the shelf life of the fruits themselves due to the heating and cooling.

  • Are you sure? I thought that one of the main components in rotting was enzymes, which are inactivated by the reducing (boiling) process. This wouldn't be like meat that's only been par-boiled possibly causing internal bacteria to spread; the main concern would be environmental bacterial contamination, which you mitigate by canning as soon as possible after boiling.
    – Aaronut
    Dec 3, 2010 at 16:56
  • @Aaronut - as far as I understand it, it depends on the cooking method and the storage method as well as acid content, etc. Something that's been canned is different than something that has been cooked and then stored in the fridge. That said my mom stores cooked pie fillings in Ball canning jars without any particular canning procedures in the fridge for ages. I've just heard that's not particularly safe.
    – justkt
    Dec 3, 2010 at 17:07
  • Sealing pie fillings in airtight jars is a great way to get botulism, unless there's enough sugar to reduce the available water to a level at which bacteria cannot grow. OR, you can add sufficient acid to achieve a pH below 4.6
    – BobMcGee
    Jul 6, 2011 at 18:15

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